A mixed number is greater than 2 3/4 but less than 2 5/6. The sum of its digits equals the greatest multiple of 6 that is less than 20. What is the mixed number?

answer: the common difference is -0.10

let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.

your answer is  

a.

5

step-by-step explanation: